She excels at a wide range of activities, including fishing, wood carving, and arm wrestling. Despite her serene and rather unemotional demeanor, she has an eccentric sense of humor and will often provoke Yūko with a variety of gags in order to gauge a reaction out of her, much to Yūko's chagrin. She has two pet dogs named Oguri Cap and Pyon. Nano is an android schoolgirl, built by the Professor. Despite being a year old, she has the height and appearance of an average teenager. She worries about keeping her identity as a robot from other people, even though the large wind-up key on her back makes it quite obvious. Her limbs will sometimes fall apart, revealing items that the Professor installed into her system without her noticing, ranging from beam-firing weapons to Swiss rolls. She acts like the Professor's caretaker, and spends her days helping her and doing all the household chores. Nano's main goal in life is to go to school, which the Professor eventually grants, resulting in her befriending Yūko's group of friends. Although she was technically never born, her "birthday" is March 7. The Professor is an intelligent eight-year-old scientist. She built Nano herself, and often makes various adjustments to her, but adamantly refuses to remove the wind-up key on her back because she thinks it is cute. Her favorite animal is the shark. She does not go to school, since she already graduated, and instead spends her days playing around in the house. Despite her intelligence, she acts like a spoiled child most of the time, as she throws tantrums to get what she wants. She likes snacking, playing around, and sharks. She also enjoys spending time with Nano's friends, particularly Yūko due to her approval of "cool things" and Mai because she gives her shark-themed chocolates and drawings. She didn't like Mai at first because she let her dogs corner her and Sakamoto on the street, but warms up to her when Mai draws a shark for her. Sakamoto is a black cat. He wears a red scarf made by the Professor, which allows him to speak. He was originally named Taisho and was Kana's pet until he fell out of the window of her house. He was then found by the Professor before mysteriously turning up at the Shinonome Lab. He decided to stay with Nano and the Professor because of his